Vector-borne diseases continue to cause significant mortality and morbidity in people throughout the world. While malaria and yellow fever are scourges of lesser-developed countries, the threat of Dengue fever is at the borders of the United States. Control of transmission of these diseases can be achieved by controlling their insect vectors. The development of mosquito transgenesis has made possible the producion of mosquitoes that have been altered by the stable insertion of exogenous genes. Our long-term goal is to produce transgenic mosquitoes that are resistant to infection by pathogens and use these as systems for studying pathogen-vector interactions as well as release organisms for programs seeking genetic control over the transmission of parasitic and viral diseases. Furthermoe, transormation makes it possible to study biochemical and molecular biological processes involved in basic aspects of mosuito physiology such as blood feeding and digestion, oogenesis and host seeking. Transposon-based genetic analysis of mosquitoes has the potential to identify many crucial genes whose expression is important for vector competence and vectorial capacity. Recently, we have shown that twso Class II transposable elements, Hermes and mariner, mediate the insertion of exogenous DNA into the chromosomes of the yellow fever mosquito. Aedes egypti (Jasinskiene et al., 1998; Coates et al., 1998). Further refinements of these transformation systems are reuqired to facilitate their use in producing pathogen- resistant mosquitoes and other strains for basic biological study.Towards these ends we propose the following specific aims: 1) develop methods for routine isolation of DNA fragments consisting of transposon-chromosome junctions from Hermes-transformed mosquito lines; 2) develop procedures and strains for remobilization of Hermes and Mariner chromosomal insertions; 3) produce transgenic strains of mosquitoes that exploit cre-loxp and FLP-FRT site-specific recombination for comparative promoter analysis. Successful accomplishment of these Specific Aim will result in robust and widely-applicable systems or mosquito transgenesis.